The present invention relates to a semiconductor integrated circuit device and, in particular, a bipolar integrated circuit device having resistance to alpha rays.
Alpha rays are generated by the nuclear decay of radioactive elements contained in such as wiring materials. When those rays enter into a semiconductor integrated circuit device, pairs of electrons and holes are generated so that collection of the electrons occurs due to causes such as funneling phenomenon. The electron collection may cause unexpected currents so that software errors may occur.
In order to reduce the electron collection, there has been employed a technique by which the concentration of impurity atoms of a semiconductor substrate is increased. This technique, however, increases capacitances of the semiconductor integrated circuit device, thereby deteriorating the operation speed of the device.